Hydraulic system for steam turbine



Aug. 16, 1960 c. E. KENNEY 2,949,122

HYDRAULIC SYSTEM FOR STEAM TURBINE 2 Sheets-Sheet 1 Filed Nov. 6, 1953klirilla, 5 ll- Aug. 16, 1960 Q KENNEY 2,949,122

HYDRAULIC SYSTEM FOR STEAM TURBINE Filed Nov. 6, 1953 2 Sheets-Sheet 2HYDRAULIC SYSTEM FOR STEAM TURBINE Clarence E. Kenney, Hartland, Wis.,assignor to Allis- Chalmers Manufacturing Company, Milwaukee, Wis.

Filed Nov. 6, 19-53, Ser. No. 390,472 2' Claims. Cl. 137-17 Thisinvention relates generally to a hydraulic system for supplying liquidunder pressure to a machine and more specifically to an improved systemin a steam turbine for supplying high pressure oil for operatingauxiliary hydraulic systems such as a governing system, :and lowpressure oil for lubrication.

It has heretofore been proposed to supply high and low pressure oil to aprime mover such as a steam turbine by providing a main centrifugal pumpdirectly coupled to the prime mover shaft. A portion of the dischargefrom the main pump which is at a high pressure is supplied to thegoverning system of the turbine and to a hydraulic turbine; theremainder of the discharge of the main pump is bypassed around thehydraulic turbine and passes through pressure reducing means to an oilcooler and then supplied to bearings of the prime mover. The hydraulicturbine derives its energy from the pressure differential between thehigh pressure in take from the main pump and low pressure discharge ofoil from the hydraulic turbine. A low pressure pump is directlyconnected to and driven by the hydraulic turbine. The low pressure pumptakes suction from a reservoir and dischargesto the intake of the mainpump.

The nature of the present invention resides in the provision of animproved hydraulic system for steam turbines whereby none of the highpressure fluid supplied by the main pump to the hydraulic turbinebypasses the hydraulic turbine to pass through pressure reducing meansfor low pressure bearing lubrication. Instead, the dischange of the lowpressure pump is utilized for bearing lubrication with the hydraulicturbine discharging to the intake of the main pump. Therefore, more ofthe energy derived from the drop in pressure from the high pressureproduced by the main pump to the low pressure required for lubrication,is utilized to operate the hydraulic turbine and low pressure pump, andnone of this energy is wastefully dissipated by bypassing the hydraulicturbine and throttling for lubrication purposes as has heretofore beendone.

It is therefore an object of the present invention to :more efficientlyutilize the available energy represented by the pressure drop betweenthe high value required for the governing system and hydraulic turbineand the low value required for lubrication.

Another object of the invention is to provide a sys-.

'tem for supplying liquid to a machine 'at two different pressures thatis more economical than prior known ;systems.

Another object of the invention is to permit the use of smaller pipingto and from the main turbine pedestal than has heretofore been used inprior known systems. Another object of the invention is to provide animproved dual fluid system for supplying liquid to a :machine at twodifferent pressures.

Objects and advantages other than those set forth above Will be apparentfrom the following description ice when read in connection with theaccompanying drawing, in which:

Fig. 1 is a diagrammatic view partly vin section of a system embodyingthe invention; and

Fig. 2 is a view similar to Fig. 1 showing a second embodiment.

Referring to the drawings, and first to Fig. 1, this invention isillustrated as applied to amachine such as a steam turbine indicatedgenerally at 1 and having a shaft 2, a lubrication system to which oilis supplied under pressure, and a servomotor indicated generally at 4 inthe governing system to which oil 'is' supplied under pressure through-aconduit 5. As is well known, the governor is arranged to control aservomotor which may be in the form of a piston 6 slidably arranged incylinder 7, for positioning a turbine inlet control valve 8. Motivefluid is supplied to the turbine 1 through an inlet conduit and thespeed and output of the turbine are controlled by regulation of thevalve 8 through the servomotor '4. Any other suitable known type ofgoverning system for turbines may be substituted for the governor andservomotor 4.

Oil for lubricating the turbine and actuating the governing system issupplied from a reservoir 12, which is customarily located at a levelbelow the turbine 1 so that the oil supplied to the bearings and othercomponents may conveniently be drained back to the reservoir 12 bygravity. The oil may be a petroleum product or any other suitable knownliquid having lubricating properties. The turbine lubricating system isdrained by means of a conduit 13. i

In accordance with the invention, a main oil pump, indicated generallyat 14, may be driven by any suitable prime mover but is preferablydirectly coupled to an extension 15 of the turbine shaft 2. As shown,this main oil pump -14 comprises a centrifugal impeller .15 mounteddirectly on the turbine shaft extension 16. The impeller is surroundedby a casing 17 which defines an annular pump inlet chamber is and adischarge scroll 21. Any suitable type of pump other than a centrifugalump may also be employed. 7

The discharge scroll 21 of the oil pump 14 communicates with a dischargepipe 22, to which is connected the servomotor supply conduit 5. Asuitable pressure regulating valve 23 may be incorporated in the conduit5 to maintain the pressure of the oil supplied to the servomotor 4constant at a preselected value. Spent liquid from the servomotor 4returns through conduit 24 to the inlet 18 of pump 14, as notedhereinafter. A suitable check valve 25 is provided in conduit 22 toprevent flow of liquid in a reverse direction through pump 14. I

Arranged in the oil reservoir 12. or in any other suitable location is ahydraulic turbine 26 consisting of a housing 27, an impeller 28, and aninlet scroll 31. A conduit 32 supplies oil under pressure from thedischarge scroll 21 of pump 14 to the inlet scroll 31 of turbine 26. Oildischarge from the turbine 26 is led by -a conduit 33 to the inletchamber 18 of the main oil pump 14. The impeller 28 of the hydraulicturbine 26 is directly connected by a shaft 34 to a pump impeller 35 ofa hydraulic pump 36. The hydraulic pump 36 is located below the level ofthe oil in reservoir 12 and may be placed within the reservoir as shown.It defines an inlet opening 37 for admitting oil from the reservoir 12to the pump impeller 35 and a pump discharge scroll 38. A conduit 41containing a check valve 42 delivers low pressure oil from the dischargescroll 38 to the inlet of trio generator (not shown) driven by steamturbine and through a reducer 44 and conduit 45, to the lubricationsystem of the steam turbine and through conduit '46 to the inlet chamberof the main oil Pump 14.

'52 similar to pump 36 located below the oil level in reservoir 12. Aninlet opening 53 is arranged to admit oil from reservoir 12 to the pump52. A conduit 54 supplies oil under pressure from the pump 52 through asuitable check valve 55 to the conduit where the oil is supplied to theservomotor 4. Another conduit 56 connects the high pressure conduit 54to a reducer 57 that reduces the pressure of incoming oil to a valuesuitable for lubrication by throttling the flow of oil passing throughthe reducer. The low pressure oil from the reducer 57 is led by aconduit 58 to the conduit 41 leading into the oil cooler 43. From theoil cooler 43, the low pressure oil is supplied through reducer 44 andconduit 45 to the lubrication system of the turbine, and through conduit46 and orifice 47 to the main pump 14 to prime the pump 14. The orifice47 also allows discharge oil from servomotor 4 to flow into the bearingsystem and to return through conduit 13 to reservoir 12 so that theservomotor can be operated when the main pump 14 is not running. Thereducer 57 is equipped with a valve 61 which is designed to close whenthe oil pressure generated by the hydraulic pump 36 after the turbine 1has been started exceeds the predetermined value of the biasing spring62 of the reducer 57.

To start the system, the motor 51 is energized and liquid is supplied bythe starting pump 52 through conduit 54 to conduit 5 to the servomotor4. Check valve 25 in conduit 22 prevents this priming liquid fromflowing backwards through the main pump 14.

When the pressure in the oil system rises to the proper value foractuating the servomotor 4, turbine 1 may be started and brought up tospeed, during which the discharge pressure of the main oil pump 14 willincrease to its normal operating value so that check valve 25 is causedto open. When the pressure in conduits 22, 32, produced by the rotationof the main oil pump impeller 15, rises above the pressure produced inconduit 54 by the starting pump 52, the check valve 55 will act toprevent any leakage of oil from conduit 22 backwards through conduit 54.

Suitable control means indicated generally at 71 may be provided for thestarting motor 51, and so arranged that the motor is automaticallydeenergized when the pressure in conduit'32 rises to a value in excessof the preselected value determined by a spring 72 in the control system71. The control system 71 comprises a toggle switch 73 which is wellknown in the art coupled to a piston 75, so that the switch 73 breaksthe circuit to motor 51 when liquid pressure in conduit 32 exceeds thepreselected value determined by the spring 72 forcing the piston 75inward. The spring 72 biases the piston 75 so that the switch 73 is in aclosed position so that motor 51 will be energized whenever the pressurein conduit 32 falls below the preselected value of spring 72.

From the above description of the apparatus, it will be apparent thatthe hydraulic system for the steam t-urbine 1 in effect comprises a highpressure circuit and a low pressure circuit interconnected by theconduit 46. The high pressure circuit comprises the main oil pump 14 inseries with the parallel connected servomoter 4 of the steam turbine 1,and the hydraulic turbine 26. The low pressure circuit comprises thehydraulic pump 36, the

a pressure suitable for operation of the servomotor 4. This pressure maybe of the order of 200 pounds per square inch, which is considerablyhigher than is ordinarily used for lubrication purposes. Therefore itbecomes necessary to reduce the pressure in some manner to a valuesuitable for the turbine lubrication system, which may be of the orderof only 15 pounds per square inch. The prior art has accomplished thisby means of a throttling valve, but the resulting throttling processwastefully dissipates an appreciable amount of the power abstracted fromthe turbine shaft 2 for driving the oil supply system.

An important feature of the invention is that the reduction of the oilpressure from the value required for operation of the servomotor 4 tothat required for the turbine lubrication system is accomplished in amanner which makes use of the energy represented by this pressure drop.This is effected by causing the pressure drop to occur across thehydraulic turbine 26 which serves to drive the hydaulic pump 36. Thismethod of conserving the energy in the oil is found to make an importantcontribution to the overall efiiciency of the prime mover by reducingthe power needed to drive the oil supply pump 14.

This improved liquid supply system provides oil at a comparatively highpressure for operating hydraulic devices such as a servomotor 4, andalso supplies oil at a much lower pressure for lubrication. This isaccomplished by the high speed main oil pump 14 coupled directly to theshaft 2 of the prime mover 1 without intermediate gearing and having thehydraulic turbine 26 arranged to positively prime the main pump 14 whenthe steam turbine 1 is at its operating speed. The hydraulic turbine 26is driven by energy derived from the drop in pressure from the highvalue required for the servomotor 4 to the lower value required forlubrication. With this improved arrangement, a minimum quantity of oilneed be handled by the main oil pump 14, so that the power required foroperating the system is kept to a minimum. By using the pressure dropinherent in the system to furnish energy for driving the hydraulic pump36, a further important improvement in the power consumption of thesystem is obtained. With this invention, a very much smaller quantity ofoil need be pumped, than in other previously suggested systems. By thusreducing the volume flow in the system, the piping to and from the mainoil pump may be smaller than in other systems. The main pump 14, thehydraulic turbine 26 and the pump 36 are designed for maximum efiiciencywith the main pump 14 delivering just enough pressure to operate theturbine 26, pump 36 and to provide the required quantity of oil to thebearings and back to the main pump 14. There is no wastage of the energyavailable from the aforementioned pressure drop since all of the oilfrom the main pump 14 passes through the hydraulic turbine 26.

In the alternative embodiment shown in Fig. 2, a system is shown forsupplying two different liquids to a steam turbine at two differentpressures. The reservoir 12 is divided by means of a plate 10 into twohydraulically independent reservoirs or compartments, one for the highpressure system utilizing a noninflammable liquid oil cooler 43 and thelubrication system of the steam V turbine connected in series.

. During normal operation of the steam turbine 1, oil is delivered bythe main pump 14 to the conduit 22 at and the other for the low pressuresystem utilizing oil.

Elements of the apparatus shown in Fig. 2 which are similar to theapparatus described in Fig. 1 are designated by the same numerals usedin Fig. 1. The high pressure circuit of Fig. 2 is similar to the highpressure circuit of Fig. 1 comprising the main pump 14, hydraulicturbine 26 and an auxiliary starting motor 51 and pump 48, none of whichare shown in section. The low pressure circuit is similar to that ofFig. 1 comprising a hydraulic pump 36, not shown in section, and oilcooler 43. The shaft 34 drivingly connecting the impeller of hydraulicturbine 26 to the impeller of hydraulic pump 36 passes through anopening in the plate 10. A suitable sealing means surrounds the shaft 34and the opening in the plate 10 to hydraulically isolate thecompartments from one another.

Instead of using a reducer 57 to provide low pressure oil to the steamturbine 1 during starting of the turbine 1, an auxiliary starting pump65 driven by a motor 64, is used to perform the same function. Thestarting pump motors 51, 64 may be of any suitable type such as anelectric motor or 'a small steam turbine. The motors 51, 64 have controlmeans 71 similar to that of Fig. 1.

The difference between the hydraulic systems shown in Fig. 1 and Fig. 2is that in Fig. 2 the high pressure cir-v cuit may utilize water or anyother noninflammable liquid since it is completely separate from the lowpressure circuit utilizing lubricating oil whereas in Fig. 1, a commonliquid is used in both the high pressure circuit and the low pressurecircuit. In Fig. 1, conduits 45, 46 connect the low pressure outlet ofthe reducer 44 with the inlet conduit 24 leading into the inlet of themain pump 14 of the high pressure system to prime the main pump 14 whenthe steam turbine is started. In Fig. 2, an auxiliary pump 77 directlyconnected to the shaft 34 of the hydraulic turbine 36 may be used toinsure adequately priming the main pump 14. It also serves as adischarge for liquid from the main servomotor 4 when the main pump 14 isnot running.

Although but two embodiments have been illustrated and described, itwill be apparent to those skilled in the art that various changes andmodifications may be made therein without departing from the spirit ofthe invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. In a hydraulic system for supplying a liquid at a high pressure and aliquid at a lower pressure to a machine, the combination of: a firstpump driven by said machine, said first pump discharging liquid at ahigh pressure; a hydraulic turbine; a first conduit connecting saidfirst pump with said hydraulic turbine so high pressure liquiddischarged from said first pump drives said hydraulic turbine; a secondconduit connecting said hydraulic turbine and said first pump so liquiddischarged from said hydraulic turbine returns to said first pump; athird conduit connecting said first pump with said machine to supplysaid high pressure liquid to said machine; a fourth conduit connectingsaid machine and said first pump so liquid supplied by said thirdconduit that is discharged from said machine returns to said first pump;said first, second, third and fourth conduits forming a first hydrauliccircuit including said first pump and said hydraulic turbine; a liquidreservoir, a second pump located in said reservoir and driven by saidhydraulic turbine, said second pump taking liquid from said reservoirand discharging said liquid at a pressure lower than said high pressure;a fifth conduit connecting said second pump with said machine to supplyliquid at said lower pressure to said machine, a sixth conduit connectedbetween said machine and said reservoir so liquid supplied by said fifthconduit that is discharged from said machine returns to said reservoir;said fifth and sixth conduits forming a second hydraulic circuitincluding said reservoir and said second pump; an auxiliary meansoperable when starting said machine for providing said high and saidlower pressure liquid including a third pump and a pressure reducingvalve, said auxiliary means arranged to automatically deenergize whensaid first pump delivers liquid at said high pressure, and a seventhconduit having an orifice, said seventh conduit connecting the suctionof said first pump to said second circuit to maintain the primedcondition of said first hydraulic circuit.

2. In a hydraulic system for supplying a liquid at a high pressure and aliquid at a lower pressure to a machine, the combination of: a firstpump driven by said machine, said first pump discharging liquid at ahigh pressure; a hydraulic turbine; a first conduit connecting .saidfirst pump with said hydraulic turbine so high pressure liquiddischarged from said first pump drives said hydraulic turbine; a secondconduit connecting said hydraulic turbine and said first pump so liquiddischarged from said hydraulic turbine returns to said first pump; athird conduit connecting said first pump with said machine to supplysaid high pressure liquid to said machine; a fourth conduit connectingsaid machine and said first pump so liquid supplied by said thirdconduit that is discharged from said machine returns to said first pump;saidfirst, second, third and fourth conduits forming a first hydrauliccircuit including said first pump and said hydraulic turbine; a liquidreservoir, a second pump located in said reservoir and driven by saidhydraulic turbine, said second pump taking liquid from said reservoirand discharging said liquid at a pressure lower than said high pressure;a fifth conduit connecting said second pump with said machine to supplyliquid at said lower pressure to said machine; a sixth conduit connectedbetween said machine and said reservoir so liquid supplied by said fifthconduit that is discharged from said machine returns to said reservoir;said fifth and sixth conduits forming a second hydraulic circuitincluding said reservoir and said second pump; a third pump operablewhen starting said machine for providing said high and said lowerpressure, a seventh conduit having an orifice, said seventh conduitconnecting the suction of said first pump to said second circuit tomaintain the primed condition of said first hydraulic circuit, and forinitially priming said first hydraulic circuit; an eighth conduitarranged to convey liquid discharged by said third pump to said firstconduit to supply liquid at high pressure to said machine, said firstconduit having a check valve to prevent reverse flow of liquid throughsaid first pump; a ninth conduit having pressure reducing means andarranged to convey liquid from said third pump to said fifth conduit tosupply liquid at lower pressure to said machine, said fifth conduithaving a check valve to prevent reverse flow of liquid through saidsecond pump.

References Cited in the file of this patent UNITED STATES PATENTS1,617,460 Schmidt Feb. 15, 1927 2,126,533 Coughey Aug. 9, 1938 2,277,569Vickers Mar. 24, 1942 2,440,980 Sheppard May 4, 1948

